J ALLERGYCLIN IMMUNOL Abstracts S69 VOLUME 109, NUMBER 1 washed out and pulmonary response had returned to baseline, albuterol (1 mg/mL) was administered by inhalation for 10 minutes, after that second MCh challenge was performed. The IL-13 treated group showed signifi- cantly increased Penh, but the combination of IL-13 and IL-I~ treated group did not. Furthermore, the inhaled 132-agonist significantly decreased the response to MCh in the IL-13 group, however, the combination group did show a significant change only at 6 and 12.5 mg/ml of MCh. From these data, we concluded that IL- 1[3decreased the response of relaxation, and IL- l3 enhanced AHR instead of affecting the response to ~2-agonist. We spec- ulated that these cytokines differently affect the airway smooth muscle in murine model. Penh values at each dose of MCh before and after albuterol MCh (mglml) 12.5 25.0 50.0 Before After Before After Before After albuterol albuteml albuteml albuterol albuterol albuteml IL-13 (n=5) 4.65 0.82 5.68 2.42 6.47 4.00 (0.50) (0.22)* (0.76) (0.42)* (0.86) (0.34)* IL-13+IL-1~ 2.69 0.59 3.49 2.52 4.06 2.92 (n=5) (0.73) (0.13)* (0.87) (1.16) (1.33) (0.84) Saline (n=5) 1.15 0.44 2.26 0.83 2.83 1.83 (0.21) (0.07)* (0.47) (0.14)* (0.60) (0.29) Each values show mean (SEM), *:p<0.05 compared with the Penh before albuterol. 166 Lack of 'F"'I3Exacerbates Pulmonary Inflammation in a M " r i n e A s t h m a M o d e l Victor Matheu, Alexandra Treschow, Vaidrius Navikas, Shohreh Issazadeh-Navikas Lund University, Lund, Sweden Anti-inflammatory properties of interferon beta (IFN-[3) has been postu- lated and shown to be effective as a therapeutic drug for patients with inflammatory disease of central nervous system, i.e. multiple sclerosis. To define the role of IFN-~ in controlling development of allergic inflamma- tion, we used an established murine model of pulmonary eosinophilic inflammation in IFN-13 knock out mice. Interestingly, our data determines that lack of IFN-~ is leading to a more severe pulmonary inflammation. A local response was mounted with production of IL-4, IL-5, and IgE in air- ways, and recruitment of eosinophils, goblet cell hyperplasia and mucus production in lung parenchyma were all significantly elevated in the absence of IFN-~. Moreover, systemic response with production of IgE and allergen-induced T cell expansion is enhanced in absence of IFN-~ gene. Higher severity of pulmonary inflammation in IFN-[3 knock-out mice could be a consequence of significantly expanded antigen-specific CD4+ T cells as a result of efficient antigen presentation by APCs and hence elevated lev- els of IgE. Indeed, we have detected higher ratio of CD4+/CD8+ T cells and significantly elevated expression of B7.1 and B7,2 on B cells and APCs cells from naive IFN-~ knock out mice. These results demonstrate that IFN- 13plays an important role in immunoregulation of the late phase asthmatic reaction. 67 Chemakine Receptor 3 Mobilizes to the Surface of Human Mast Cells in Response to IgE-Mediated Activation and Potentiates Their Generation of IL-13 and IL-4 KS Price, EA Mellor, DS Friend, N De Jesus, Joshua A Boyce Brigham and Women's Hospital, Boston, MA Human mast cells (hMCs) express the cell membrane-associated C-C chemokine receptor (CCR3) for eotaxin-1, -2, -3 and related chemokines. Stimulation of cord blood-derived hMCs with eotaxin-1 produces a sus- tained rise in intracellular calcium. We now report that both nasal polyp- associated hMCs and cord blood-derived hMCs possess additional CCR3 stores in a secretory granule-like distribution. Following overnight passive sensitization and challenge with anti-IgE, IL-4 primed cord blood-derived hMCs increase their cell surface expression of CCR3 within 30 minutes, and sustain this for up to 6 hours as determined by flow cytometry and immuno- fluorescence. This increase in membrane CCR3 is insensitive to cyclobexa- mide and actinomycin D, suggesting mobilization of preformed stores. Recombinant eotaxin-1 (1-100ng/ml) failed to induce exocytosis or cytokine generation by itself, but augmented histamine release when com- bined with submaximal levels of anti-IgE. Moreover, this concomitant anti- IgE/eotaxin- 1 stimulation augmented IL- 13 generation 2 fold over that pro- duced by hMCs activated by anti-IgE alone, and unexpectedly induced a dose-dependent de novo production of IL-4 as well. When eotaxin-1 was added 2-3 hours after anti-IgE so as to coincide with maximal membrane CCR3 expression, a further 2-fold increase in IL-13 generation over that produced by hMCs concomitantly stimulated by anti-IgE and eotaxin-1 was observed; in contrast, IL-4 production progressively decreased with longer delays in eotaxin- 1 addition. Thus, hMCs store the important allergy-associ- ated chemokine receptor, CCR3 within their secretory granules, and mobi- lize this receptor to their surface with IgE-dependent exocytosis, providing the receptor for eotaxin-1 mediated costimulation which then augments the key Th2 cytokines IL- 13 and IL-4, by apparently separate pathways. l~g Anti-lL-4 Receptor mAb Attenuates Allergic Airway Hyperre- VU sponsiveness(AHR) and Inflammation in Allergic Mice Eun-Seok Yang*, Anthony Joetham*, Katsuyuki Takeda*, Zhi-Hua Cui*, Christian Taube*, Joel Tocker§, Erwin W Gelfand* *National Jewish Medical and Research Center, Denver, CO §Immunex Corporation, Seat- tle, WA IL-4, a Th-2 cytokine, has been implicated in airway hyperresponsive- ness, pulmonary inflammation, eosinophilia and IgE production. Concern has been expressed that interfering with IL-4 may not be of benefit in previ- ously sensitized hosts~ We evaluated AHR and airway inflammation by depleting available levels of secreted IL-4 using sIL-4R or blocking the action of IL-4 receptor by giving anti-IL-4R mAb in a secondary challenge model. BALB/c mice were first sensitized to ovalbumin (OVA) by intraperitoneal injection on days 1 and 14, followed by aerosol challenge with 1% OVA on days 26, 27, 28to elicit acute (primary) AHR and lung eosinophilia. Four to six weeks following the last challenge, AHR and air- way inflammation were completely resolved: AHR and airway inflamma- tion could be triggered by a single allergen provocation 4-6 weeks after the last challenge. Anti-IL-4R mAb and sIL-4R were given i.v. or i.p., 1 hr prior to secondary provocation and airway responsiveness to aerosolized metha- choline (MCh), lung eosinophilia, serum immunoglobulin levels and bron- choalveolar lavage fluid (BALF) cytokine levels were assessed 48 hr later. Previously sensitized and challenged mice (IPN) developed significant air- way eosinophilia and heightened AHR to MCh compared to nonsensitized animals, sIL-4R treatment had little effect on AHR and airway inflamma- tion at this time. In contrast, administration of anti-IL-4R mAb decreased AHR as well as BALF eosinophilia in a dose-dependent fashion. OVA-spe- cific IgE and IL-4 levels were also significantly decreased in anti-IL-4R treated mice. A nonblocking anti-IL-4R mAb was without any effect. There were no significant changes in total IgE, OVA-specific IgG1, OVA-specific IgG2a, IL-5 and IFN-y. These results demonstrate that anti-IL-4R mAb may have benefit in the treatment of allergic airway disease, even in previ- ously sensitized hosts.